Building the non-redundant sequence set. The schema depicts an example for the establishment of the NR sequence set for a gene with three splicing variants. The different fragments are grouped according to their presence across all transcripts as described in the main text. Notice that these fragments (coloured) comprise only the central positions of all possible 19-mers and therefore transcript ends are not included (blank boxes at the top of the Figure). However, in the final NR sequence set (bottom) the 5' and 3' ends will be added to their corresponding fragments and the ends of the other fragments will be extended until they account for the full-length sequences of all 19-mers they represent. The philosophy behind this procedure is similar to that previously described by others .